Phosphinimine amido-ether complexes

ABSTRACT

Provided in this disclosure are organometallic complexes that contain i) a metal atom selected from Hf and Zr; 2) a phosphinimine ligand; 3) an amido-ether ligand and at least one other ancillary ligand. The use of such a complex, in combination with an activator, as an olefin polymerization catalyst is demonstrated. The catalysts are effective for the copolymerization of ethylene with an alpha olefin (such as 1-butene, 1-hexene, or 1-octene) and enable the production of high molecular weight copolymers (Mw greater than 25,000) with good comonomer incorporation at high productivity.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of the filing date of U.S.Provisional Application No. 62/662,915, which was filed on Apr. 26,2018. The contents of U.S. Application 62/662,915 are incorporated byreference in their entirety.

TECHNICAL FIELD

The present disclosure relates to a new family of group 4 organometalliccomplexes having a phosphinimne ligand and an amido-ether ligand andolefin polymerization catalyst systems that employ these complexes.

BACKGROUND

Bis(phosphinimine) complexes of titanium, and the use of these complexesas olefin polymerization catalysts, are disclosed in United StatesPatent Number (U.S. Pat. No. 6,239,238 (Brown et al., to NOVA ChemicalsInternational S.A.).

Titanium complexes having a cyclopentadienyl ligand and a phosphinimineligand, and the use of such complexes as olefin polymerizationcatalysts, is disclosed in U.S. Pat. No. 6,063,879 (Stephan et al, toNOVA Chemicals International S.A.). Organometallic complexes having aphosphinimine ligand and another heteroatom ligand are disclosed in U.S.Pat. No. 6,147,172 (Brown et al., to NOVA Chemicals International S.A.).

Organometallic complexes (based on a group 3 to group 8 metal) that havetwo heteroatoms x and y (with each of x and y being selected from N, O,S, and P) that are connected by a bridging group are disclosed inseveral patents in the name of Murray (See U.S. Pat. Nos. 6,103,657;6,320,005; and 6,610,627 (Murray; to Union Carbide Corporation)). Theuse of several of these complexes as catalysts for olefin polymerizationis also disclosed. Published U.S. application 2002/049288 Goh et al.)also makes a similar disclosure to the Murray Patents.

SUMMARY

In one embodiment, the present disclosure provides a complex having theformula (PI)(AE)ML₂, wherein:

I) PI is a phosphinimine ligand defined by the formula:

where each R¹ is independently selected from a group consisting of ahydrogen atom; a C₁₋₃₀ hydrocarbyl radical, which hydrocarbyl radical isunsubstituted or further substituted by a halogen atom; a C₁₋₁₀ alkoxyradical; a C₆₋₁₀ aryl or aryloxy radical; an amido radical; a silylradical or a germanyl radical; II) AE is an amido-ether ligand definedby the formula:

where Q is a bridging group between oxygen, 0 and nitrogen, N², andcontains one or more atoms selected from group consisting of Group 13 to16 elements; R² is a group containing 1 to 50 atoms selected from thegroup consisting of hydrogen and Group 13 to 17 elements; R³ is a groupcontaining 1 to 50 atoms selected from the group consisting of hydrogenand Group 13 to 17 elements; and wherein the R² group optionally joinstogether with the bridging group Q;

III) each L is an activatable ligand; and

IV) M is a metal selected from the group consisting of Zr and Hf, andwherein N¹, N² and optionally 0 are bonded to M.

In another embodiment, the present disclosure provides an olefinpolymerization catalyst system comprising

1) a phosphinimine/amido-ether complex defined above; and

2) an activator.

In another embodiment, the present disclosure provides a process for thepolymerization of olefins employing the olefin polymerization catalystsystem defined above.

BRIEF DESCRIPTION OF THE DRAWING

The FIGURE illustrates rates of ethylene consumption.

DETAILED DESCRIPTION

Amido Ether Ligand

AE is an amido-ether ligand defined by the formula:

where Q is a bridging group between oxygen, O and nitrogen, N², andcontains one or more atoms selected from group consisting of Group 13 to16 elements; R² is a group containing 1 to 50 atoms selected from thegroup consisting of hydrogen and Group 13 to 17 elements; R³ is a groupcontaining 1 to 50 atoms selected from the group consisting of hydrogenand Group 13 to 17 elements; and wherein the R² group optionally joinstogether with the bridging group Q.

In an embodiment, the bridge Q is an aryl group. In an embodiment, the Natom and the O atom of the above formula are substituents on adjacentatoms of an aryl group (as illustrated for example, by theorganometallic complex shown in Example 1 of the present examples).

In an embodiment, the 0 atom is part of a furan ring.

Phosphinimine Ligand

The phosphinimine ligand is defined by the formula: R¹3P═N—, where Nbonds to the metal, and wherein each R¹ is independently selected fromthe group consisting of a hydrogen atom; a halogen atom; C₁₋₂₀hydrocarbyl radicals which are unsubstituted or further substituted byone or more halogen atom and/or C₁₋₂₀ alkyl radical; C₁₋₈ alkoxyradical; C₆₋₁₀ aryl or aryloxy radical (the aryl or aryloxy radicaloptionally being unsubstituted or further substituted by one or morehalogen atom and/or C₁₋₂₀ alkyl radical); amido radical; silyl radicalof the formula: —SiR′3 wherein each R′ is independently selected fromthe group consisting of hydrogen, a C₁₋₈ alkyl or alkoxy radical, C₆₋₁₀aryl or aryloxy radicals; and germanyl radical of the formula: -GeR′3wherein R′ is as defined above.

In an embodiment of the disclosure the phosphinimine ligand is chosen sothat each R is a hydrocarbyl radical. In a particular embodiment of thedisclosure, the phosphinimine ligand is tri-(tertiarybutyl)phosphinimine(i.e. where each R¹ is a tertiary butyl group, or “t-Bu” for short).

Activatable Ligand

The term “activatable ligand” refers to a ligand which may be activatedby a cocatalyst (also referred to as an “activator”), to facilitateolefin polymerization. An activatable ligand L may be cleaved from themetal center M via a protonolysis reaction or abstracted from the metalcenter M by suitable acidic or electrophilic catalyst activatorcompounds (also known as “co-catalyst” compounds) respectively, examplesof which are described below. The activatable ligand L may also betransformed into another ligand which is cleaved or abstracted from themetal center M (e.g., a halide may be converted to an alkyl group).Without wishing to be bound by any single theory, protonolysis orabstraction reactions generate an active “cationic” metal center whichcan polymerize olefins. In embodiments of the present disclosure, theactivatable ligand, L is independently selected from the groupconsisting of a hydrogen atom; a halogen atom; a C₁₋₁₀ hydrocarbylradical; a C₁₋₁₀ alkoxy radical; a C₆₋₁₀ aryl oxide radical, each ofwhich said hydrocarbyl, alkoxy, and aryl oxide radicals may beunsubstituted by or further substituted by a halogen atom, a C₁₋₈ alkylradical, a C₁₋₈ alkoxy radical, a C₆₋₁₀ aryl or aryloxy radical; anamido radical which is unsubstituted or substituted by up to two C₁₋₈alkyl radicals; and a phosphido radical which is unsubstituted orsubstituted by up to two C₁₋₈ alkyl radicals. Two activatable L ligandsmay also be joined to one another and form for example, a substituted orunsubstituted diene ligand (e.g., 1,3-diene); or a delocalizedheteroatom containing group such as an acetate group.

The number of activatable ligands depends upon the valency of the metaland the valency of the activatable ligand. In some embodiments, thepreferred phosphinimine catalysts are based on group 4 metals in theirhighest oxidation state (i.e. 4⁺). Particularly suitable activatableligands are monoanionic such as a halide (e.g., chloride) or ahydrocarbyl (e.g., methyl, benzyl).

In some instances, the metal of the phosphinimine catalyst may not be inthe highest oxidation state. For example, a titanium (III) componentwould contain only one activatable ligand.

The Activator

In the present disclosure, the single site catalyst is used incombination with at least one activator (or “cocatalyst”) to form anactive polymerization catalyst system for olefin polymerization.Activators (i.e. cocatalysts) include ionic activator cocatalysts andaluminoxane cocatalysts.

Aluminoxane (Also Referred to as Alkylaluminoxane)

The activator used to activate the single site catalyst can be anysuitable activator including one or more activators selected from thegroup consisting of alkylaluminoxanes and ionic activators, optionallytogether with an alkylating agent. Without wishing to be bound bytheory, the alkylaluminoxanes are complex aluminum compounds of theformula: R⁴ ₂Al¹O(R⁴Al¹O)_(m)Al¹R⁴ ₂, wherein each R⁴ is independentlyselected from the group consisting of C₁₋₂₀ hydrocarbyl radicals and mis from 3 to 50. Optionally, a hindered phenol can be added to thealkylaluminoxane to provide a molar ratio of Al¹:hindered phenol of from2:1 to 5:1 when the hindered phenol is present.

In an embodiment of the disclosure, R³ of the alkylaluminoxane, is amethyl radical and m is from 10 to 40.

The alkylaluminoxanes are typically used in substantial molar excesscompared to the amount of group 4 transition metal in the single sitecatalyst. The Al¹:group 4 transition metal molar ratios are from 10:1 to10,000:1, such as about 30:1 to 500:1.

It is well known in the art, that the alkylaluminoxane can serve dualroles as both an alkylator and an activator. Hence, an alkylaluminoxaneactivator is often used in combination with activatable ligands such ashalogens.

Alternatively, the activator of the present disclosure may be acombination of an alkylating agent (which may also serve as a scavenger)with an activator capable of ionizing the group 4 metal of the singlesite catalyst (i.e. an ionic activator). In this context, the activatorcan be chosen from one or more alkylaluminoxane and/or an ionicactivator.

When present, the alkylating agent may be selected from the groupconsisting of (R*)_(p)MgX² _(2-p) wherein X² is a halide and each R* isindependently selected from the group consisting of C₁₋₁₀ alkyl radicalsand p is 1 or 2; R*Li wherein in R* is as defined above, (R*)_(q)ZnX²_(2-q) wherein R* is as defined above, X² is halogen and q is 1 or 2;(R⁴)_(s)Al²X² _(3-s) wherein R* is as defined above, X² is halogen and sis an integer from 1 to 3. In some embodiments, R* is a C₁₋₄ alkylradical, and X² is chlorine. Commercially available compounds includetriethyl aluminum (TEAL), diethyl aluminum chloride (DEAC), dibutylmagnesium ((Bu)₂Mg), and butyl ethyl magnesium (BuEtMg or BuMgEt).

Ionic Activator

The ionic activator may be selected from the group consisting of: (i)compounds of the formula [R⁵]⁺ [B(R⁶)₄]⁻ wherein B is a boron atom, R⁵is a cyclic C₅₋₇ aromatic cation or a triphenyl methyl cation and eachR⁶ is independently selected from the group consisting of phenylradicals which are unsubstituted or substituted with from 3 to 5substituents selected from the group consisting of a fluorine atom, aC₁₋₄ alkyl or alkoxy radical which is unsubstituted or substituted by afluorine atom; and a silyl radical of the formula —Si—(R⁷)₃; whereineach R⁷ is independently selected from the group consisting of ahydrogen atom and a C₁₋₄ alkyl radical; and (ii) compounds of theformula [(R⁸)_(t)ZH]⁺ [B(R⁶)₄]⁻ wherein B is a boron atom, H is ahydrogen atom, Z is a nitrogen atom or phosphorus atom, t is 2 or 3 andR⁸ is selected from the group consisting of C₁₋₅ alkyl radicals, aphenyl radical which is unsubstituted or substituted by up to three C₁₋₄alkyl radicals, or one R⁸ taken together with a nitrogen atom may forman anilinium radical and R⁶ is as defined above; and (iii) compounds ofthe formula B(R⁶)₃ wherein R⁶ is as defined above.

In some embodiments, in the above compounds, preferably R⁶ is apentafluorophenyl radical, and R⁵ is a triphenylmethyl cation, Z is anitrogen atom and R⁸ is a C₁₋₄ alkyl radical or one R⁸ taken togetherwith a nitrogen atom forms an anilinium radical (e.g., PhR⁸ ₂NH⁺, whichis substituted by two R⁸ radicals such as for example two C₁₋₄ alkylradicals).

Examples of compounds capable of ionizing the single site catalystinclude the following compounds: triethylammonium tetra(phenyl)boron,tripropylammonium tetra(phenyl)boron, tri(n-butyl)ammoniumtetra(phenyl)boron, trimethylammonium tetra(p-tolyl)boron,trimethylammonium tetra(o-tolyl)boron, tributylammoniumtetra(pentafluorophenyl)boron, tripropylammoniumtetra(o,p-dimethylphenyl)boron, tributylammoniumtetra(m,m-dimethylphenyl)boron, tributylammoniumtetra(p-trifluoromethylphenyl)boron, tributylammoniumtetra(pentafluorophenyl)boron, tri(n-butyl)ammonium tetra(o-tolyl)boron,N,N-dimethylanilinium tetra(phenyl)boron, N,N-diethylaniliniumtetra(phenyl)boron, N,N-diethylanilinium tetra(phenyl)n-butylboron,N,N-2,4,6-pentamethylanilinium tetra(phenyl)boron,di-(isopropyl)ammonium tetra(pentafluorophenyl)boron,dicyclohexylammonium tetra (phenyl)boron, triphenylphosphoniumtetra)phenyl)boron, tri(methylphenyl)phosphonium tetra(phenyl)boron,tri(dimethylphenyl)phosphonium tetra(phenyl)boron, tropilliumtetrakispentafluorophenyl borate, triphenylmethyliumtetrakispentafluorophenyl borate, benzene (diazonium)tetrakispentafluorophenyl borate, tropilliumphenyltris-pentafluorophenyl borate, triphenylmethyliumphenyl-trispentafluorophenyl borate, benzene (diazonium)phenyltrispentafluorophenyl borate, tropillium tetrakis(2,3,5,6-tetrafluorophenyl) borate, triphenylmethylium tetrakis(2,3,5,6-tetrafluorophenyl) borate, benzene (diazonium) tetrakis(3,4,5-trifluorophenyl) borate, tropillium tetrakis(3,4,5-trifluorophenyl) borate, benzene (diazonium) tetrakis(3,4,5-trifluorophenyl) borate, tropillium tetrakis(1,2,2-trifluoroethenyl) borate, trophenylmethylium tetrakis(1,2,2-trifluoroethenyl) borate, benzene (diazonium) tetrakis(1,2,2-trifluoroethenyl) borate, tropillium tetrakis(2,3,4,5-tetrafluorophenyl) borate, triphenylmethylium tetrakis(2,3,4,5-tetrafluorophenyl) borate, and benzene (diazonium) tetrakis(2,3,4,5-tetrafluorophenyl) borate.

Commercially available activators which are capable of ionizing thegroup 4 metal of the single site catalyst include:

N,N-dimethylaniliniumtetrakispentafluorophenyl borate(“[Me₂NHPh][B(C₆F₅)₄]”); triphenylmethylium tetrakispentafluorophenylborate (“[Ph₃C][B(C₆F₅)₄]”); and trispentafluorophenyl boron and MAO(methylaluminoxane) and MMAO (modified methylaluminoxane).

The ionic activators compounds may be used in amounts which provide amolar ratio of group 4 transition metal to boron that will be from 1:1to 1:6. Optionally, mixtures of alkylaluminoxanes and ionic activatorscan be used as activators in the polymerization catalyst.

Catalyst System

The catalyst precursor, the activator, or the entire catalystcomposition may be impregnated onto a solid, inert support, in liquidform such as a solution, dispersion or neat liquid, spray dried, in theform of a prepolymer, or formed in-situ during polymerization.

In the case of a supported catalyst composition, the catalystcomposition may be impregnated in or deposited on the surface of aninert substrate such as silica, carbon black, polyethylene,polycarbonate porous crosslinked polystyrene, porous crosslinkedpolypropylene, alumina, thoria, zirconia, or magnesium halide (e.g.,magnesium dichloride), such that the catalyst composition is between 0.1and 90 percent by weight of the total weight of the catalyst compositionand the support.

Polymerization Process

The catalyst composition may be used for the polymerization of olefinsby any suspension, solution, slurry, or gas phase process, using knownequipment and reaction conditions, and is not limited to any specifictype of reaction system.

Generally, olefin polymerization temperatures range from about 0° C. toabout 200° C. at atmospheric, subatmospheric, or superatmosphericpressures. Slurry or solution polymerization processes may utilizesubatmospheric or superatmospheric pressures and temperatures in therange of about 40° C. to about 110° C. A useful liquid phasepolymerization reaction system is described in U.S. Pat. No. 3,324,095.Liquid phase reaction systems generally comprise a reactor vessel towhich olefin monomer and catalyst composition are added, and whichcontains a liquid reaction medium for dissolving or suspending thepolyolefin. The liquid reaction medium may consist of the bulk liquidmonomer or an inert liquid hydrocarbon that is nonreactive under thepolymerization conditions employed. Although such an inert liquidhydrocarbon need not function as a solvent for the catalyst compositionor the polymer obtained by the process, it usually serves as solvent forthe monomers employed in the polymerization. Among the inert liquidhydrocarbons suitable for this purpose are isopentane, hexane,cyclohexane, heptane, benzene, toluene, and the like. Reactive contactbetween the olefin monomer and the catalyst composition should bemaintained by constant stirring or agitation. The reaction mediumcontaining the olefin polymer product and unreacted olefin monomer iswithdrawn from the reactor continuously. The olefin polymer product isseparated, and the unreacted olefin monomer and liquid reaction mediumare recycled into the reactor.

1. Gas Phase

When gas phase polymerization is employed, pressures may be in the rangeof 1 to 1000 psi, such as 50 to 400 psi, for example 100 to 300 psi, andtemperatures in the range of 30° C. to 130° C., for example 65° C. to110° C. Stirred or fluidized bed gas phase reaction systems areparticularly useful. Generally, a conventional gas phase, fluidized bedprocess is conducted by passing a stream containing one or more olefinmonomers continuously through a fluidized bed reactor under reactionconditions and in the presence of catalyst composition at a velocitysufficient to maintain a bed of solid particles in a suspendedcondition. A stream containing unreacted monomer is withdrawn from thereactor continuously, compressed, cooled, optionally fully or partiallycondensed as disclosed in U.S. Pat. Nos. 4,528,790 and 5,462,999, andrecycled to the reactor. Product is withdrawn from the reactor andmake-up monomer is added to the recycle stream. As desired fortemperature control of the system, any gas inert to the catalystcomposition and reactants may also be present in the gas stream.

Polymerization may be carried out in a single reactor or in two or morereactors in series, and is conducted substantially in the absence ofcatalyst poisons. Organometallic compounds may be employed as scavengingagents for poisons to increase the catalyst activity. Examples ofscavenging agents are metal alkyls, including aluminum alkyls, such astriisobutylaluminum.

Conventional adjuvants may be included in the process, provided they donot interfere with the operation of the catalyst composition in formingthe desired polyolefin. Hydrogen or a metal or non-metal hydride (e.g.,a silyl hydride) may be used as a chain transfer agent in the process.Hydrogen may be used in amounts up to about 10 moles of hydrogen permole of total monomer feed.

Olefin polymers that may be produced according to the disclosureinclude, but are not limited to, ethylene homopolymers, homopolymers oflinear or branched higher alpha-olefins containing 3 to about 20 carbonatoms, and interpolymers of ethylene and such higher alpha-olefins, withdensities ranging from about 0.86 to about 0.96. Suitable higheralpha-olefins include, for example, propylene, 1-butene, 1-pentene,1-hexene, 4-methyl-1-pentene, 1-octene, and 3,5,5-trimethyl-1-hexene.Olefin polymers according to the disclosure may also be based on orcontain conjugated or non-conjugated dienes, such as linear, branched,or cyclic hydrocarbon dienes having from about 4 to about 20 carbonatomes, for example 4 to 12 carbon atoms. In some embodiments, preferreddienes include 1,4-pentadiene, 1,5-hexadiene, 5-vinyl-2-norbornene,1,7-octadiene, vinyl cyclohexene, dicyclopentadiene, butadiene,isobutylene, isoprene, ethylidene norbornene and the like. Aromaticcompounds having vinyl unsaturation such as styrene and substitutedstyrenes, and polar vinyl monomers such as acrylonitrile, maleic acidesters, vinyl acetate, acrylate esters, methacrylate esters, vinyltrialkyl silanes and the like may be polymerized according to thedisclosure as well. Specific olefin polymers that may be made accordingto the disclosure include, for example, polyethylene, polypropylene,ethylene/propylene rubbers (EPR's), ethylene/propylene/diene terpolymers(EPDM's), polybutadiene, polyisoprene and the like.

2. Slurry Process

Detailed descriptions of slurry polymerization processes are widelyreported in the patent literature. For example, particle formpolymerization, or a slurry process where the temperature is kept belowthe temperature at which the polymer goes into solution is described inU.S. Pat. No. 3,248,179. Slurry processes include those employing a loopreactor and those utilizing a single stirred reactor or a plurality ofstirred reactors in series, parallel, or combinations thereof.Non-limiting examples of slurry processes include continuous loop orstirred tank processes. Further examples of slurry processes aredescribed in U.S. Pat. No. 4,613,484.

Slurry processes are conducted in the presence of a hydrocarbon diluentsuch as an alkane (including isoalkanes), an aromatic, or a cycloalkane.The diluent may also be the alpha olefin comonomer used incopolymerizations. Alkane diluents include propane, butanes, (i.e.normal butane and/or isobutane), pentanes, hexanes, heptanes, andoctanes. The monomers may be soluble in (or miscible with) the diluent,but the polymer is not (under polymerization conditions). Thepolymerization temperature can be from about 5° C. to about 200° C. Insome embodiments, the polymerization temperature is less than about 120°C., such as from about 10° C. to about 100° C. The reaction temperatureis selected so that an ethylene copolymer is produced in the form ofsolid particles. The reaction pressure is influenced by the choice ofdiluent and reaction temperature. For example, pressures may range from15 to 45 atmospheres (about 220 to 660 psi or about 1500 to about 4600kPa) when isobutane is used as diluent (see, for example, U.S. Pat. No.4,325,849) to approximately twice that (i.e. from 30 to 90atmospheres—about 440 to 1300 psi or about 3000 to 9100 kPa) whenpropane is used (see, for example, U.S. Pat. No. 5,684,097). Thepressure in a slurry process must be kept sufficiently high to keep atleast part of the ethylene monomer in the liquid phase. The reactiontypically takes place in a jacketed closed loop reactor having aninternal stirrer (e.g., an impeller) and at least one settling leg.Catalyst, monomers and diluents are fed to the reactor as liquids orsuspensions. The slurry circulates through the reactor and the jacket isused to control the temperature of the reactor. Through a series of letdown valves the slurry enters a settling leg and then is let down inpressure to flash the diluent and unreacted monomers and recover thepolymer generally in a cyclone. The diluent and unreacted monomers arerecovered and recycled back to the reactor.

3. Solution Polymerization

Solution processes for the copolymerization of ethylene and an alphaolefin having from 3 to 12 carbon atoms are well known in the art. Theseprocesses are conducted in the presence of an inert hydrocarbon solventtypically a C₅₋₁₂ hydrocarbon which may be unsubstituted or substitutedby a C₁₋₄ alkyl group, such as pentane, methyl pentane, hexane, heptane,octane, cyclohexane, methylcyclohexane and hydrogenated naphtha. Anexample of a suitable solvent which is commercially available is ISOPAR™E (C₈₋₁₂ aliphatic solvent, Exxon Chemical Co.).

In general, a solution polymerization process may use one, two (or more)polymerization reactors.

In an embodiment, the polymerization temperature in at least one CSTR(continuous stirred tank reactor) is from about 80° C. to about 280° C.(e.g., from about 120° C. to 220° C.) and a tubular reactor is operatedat a slightly higher temperature. Cold feed (i.e. chilled solvent and/ormonomer) may be added to the CSTR(s). The polymerization enthalpy heatsthe reactor. The polymerization solution which exits in the reactor maybe more than 100° C. hotter than the reactor feed temperature. Agitationefficiency in the CSTR may be determined by measuring the reactortemperature at several different points. The largest temperaturedifference (i.e. between the hottest and coldest temperaturemeasurements) is described as the internal temperature gradient for thepolymerization reactor. A very well mixed CSTR has a maximum internaltemperature gradient of less than 10° C. An example agitator system isdescribed in copending and commonly assigned U.S. Pat. No. 6,024,483. Insome embodiments, preferred pressures are from about 500 psi to 8,000psi. In some embodiments, the preferred reaction process is a “mediumpressure process”, which means that the pressure in each reactor is lessthan about 6,000 psi (about 41,000 kiloPascals or kPa)—for example, fromabout 1,500 psi to 3,000 psi (about 10,000-21,000 kPa).

If more than one CSTR is employed, catalyst can be added to each of theCSTR(s) in order to maintain a high reactor rate. The catalyst used ineach CSTR may be the same or different, but it is generally preferableto use the same type of catalyst in each CSTR. In some embodiments, atleast 60 weight % of the ethylene fed to the CSTR(s) is polymerized topolyethylene in the CSTR(s). For example, at least 70 weight % of theethylene fed to the CSTR(s) can be polymerized to polyethylene in theCSTR(s).

If it is desired to use a mixed catalyst system in which one catalyst isa single site catalyst and one catalyst is a Ziegler-Natta (Z/N)catalyst, then the single site catalyst can be employed in the firstCSTR and the Z/N catalyst can be employed in the second CSTR.

A tubular reactor that is connected to the discharge of the at least onCSTR may also be employed. If two CSTR's are used in series, then thetubular reactor receives the discharge from the second CSTR.

The term “tubular reactor” is meant to convey its conventional meaning:namely a simple tube. The tubular reactor of this disclosure will have alength/diameter (L/D) ratio of at least 10/1. The tubular reactor is notagitated. The tubular reactor can be operated adiabatically. Thus, aspolymerization progresses, the remaining comonomer is increasinglyconsumed and the temperature of the solution increases (both of whichimprove the efficiency of separating the remaining comonomer from thepolymer solution). The temperature increase along the length of thetubular reactor may be greater than 3° C. (i.e. that the dischargetemperature from the tubular reactor is at least 3° C. greater than thedischarge temperature from the CSTR that feeds the tubular reactor).

Optionally, the tubular reactor may also have feed ports for additionalcatalyst, cocatalyst, comonomer and/or telomerization agent (such ashydrogen). However, in some embodiments, preferably no additionalcatalyst is added to the tubular reactor.

The total volume of the tubular reactor can be at least 10 volume % ofthe volume of the at least one CSTR, especially from 30% to 200% (forclarity, if the volume of the CSTR is 1000 liters, then the volume ofthe tubular reactor is at least 100 liters; for example, from 300 to2000 liters).

Addition of Monomers and Solvent

Suitable monomers for copolymerization with ethylene include C₃₋₁₂ alphaolefins which are unsubstituted or substituted by up to two C₁₋₆ alkylradicals. Illustrative non-limiting examples of such alpha-olefins areone or more of propylene, 1-butene, 1-pentene, 1-hexene, 1-octene and1-decene. In some embodiments, octene-1 is preferred.

In an embodiment, the monomers are dissolved/dispersed in the solventeither prior to being fed to the first CSTR (or for gaseous monomers themonomer may be fed to the reactor so that it will dissolve in thereaction mixture). Prior to mixing, the solvent and monomers aregenerally purified to remove potential catalyst poisons such as water,oxygen or other polar impurities. The feedstock purification followsstandard practices in the art, e.g. molecular sieves, alumina beds andoxygen removal catalysts are used for the purification of monomers. Thesolvent itself as well (e.g., methyl pentane, cyclohexane, hexane ortoluene) can be treated in a similar manner.

Generally, the catalyst components may be premixed in the solvent forthe reaction or fed as separate streams to each reactor.

In some instances, premixing may be desirable to provide a reaction timefor the catalyst components prior to entering the first CSTR. Such an“in-line mixing” technique is described in the patent literature (mostnotably U.S. Pat. No. 5,589,555, issued Dec. 31, 1996 to DuPont CanadaInc.).

The residence time in each reactor will depend on the design and thecapacity of the reactor. Generally, the reactors can be operated underconditions to achieve a thorough mixing of the reactants. As previouslynoted, the polymerization reactors are arranged in series (i.e. with thesolution from the at least one CSTR being transferred to the tubularreactor).

EXAMPLES General General Experimental Methods

All reactions involving air and/or moisture sensitive compounds wereconducted under nitrogen using standard Schlenk and glovebox techniques.Reaction solvents were purified using the system described by Grubbs etal. (see Pangborn, A. B.; Giardello, M. A.; Grubbs, R. H.; Rosen R. K.;Timmers, F. J. Organometallics 1996, 15, 1518-1520) and then stored overactivated molecular sieves in an inert atmosphere glovebox.Triphenylcarbenium tetrakis(pentafluorophenyl)borate was purchased fromAlbemarle Corp. and used as received. The phosphinimine ligand t-Bu₃PNHand (t-Bu₃PN)TiMe₃ were prepared using the established methods (seeStephan, D. W. et al. Can. J. Chem. 2003, 81, 1471-1476 and Stephan, D.W. et al. Organometallics 2000, 19, 2994-3000, respectively). Thehafnium complex [(2-(OMe)C₆H₄)(2,4,6-Me₃C₆H₂)N]Hf(CH₂Ph)₃ was preparedas described by Murphy, V. et al. in J. Am. Chem. Soc. 2003, 125,4306-4317. Deuterated solvents were purchased from Sigma Aldrich(toluene-d₈) and were stored over 4 Å molecular sieves prior to use. NMRspectra were recorded on a Bruker 400 MHz spectrometer (¹H NMR at 400.1MHz, ³¹P NMR at 162 MHz, and ¹⁹F NMR at 376 MHz).

Molecular weight information (M_(w), M_(n) and M_(z) in g/mol) andmolecular weight distribution (M_(w)/M_(n)), and z-average molecularweight distribution (M_(z)/M_(w)) were analyzed by gel permeationchromatography (GPC), using an instrument sold under the trade name“Waters 150c”, with 1,2,4-trichlorobenzene as the mobile phase at 140°C. The samples were prepared by dissolving the polymer in this solventand were run without filtration. Molecular weights are expressed aspolyethylene equivalents with a relative standard deviation of 2.9% forthe number average molecular weight (“Mn”) and 5.0% for the weightaverage molecular weight (“Mw”). Polymer sample solutions (1 to 2 mg/mL)were prepared by heating the polymer in 1,2,4-trichlorobenzene (TCB) androtating on a wheel for 4 hours at 150° C. in an oven. The antioxidant2,6-di-tert-butyl-4-methylphenol (BHT) was added to the mixture in orderto stabilize the polymer against oxidative degradation. The BHTconcentration was 250 ppm. Sample solutions were chromatographed at 140°C. on a PL 220 high-temperature chromatography unit equipped with fourShodex columns (HT803, HT804, HT805 and HT806) using TCB as the mobilephase with a flow rate of 1.0 mL/minute, with a differential refractiveindex (DRI) as the concentration detector. BHT was added to the mobilephase at a concentration of 250 ppm to protect the columns fromoxidative degradation. The sample injection volume was 200 mL. The rawdata were processed with CIRRUS® GPC software. The columns werecalibrated with narrow distribution polystyrene standards. Thepolystyrene molecular weights were converted to polyethylene molecularweights using the Mark-Houwink equation, as described in the ASTMstandard test method D6474.

The branch frequency of copolymer samples (i.e., the short chainbranching, SCB per 1000 carbons) and the C₆ comonomer content (in wt %)was determined by Fourier Transform Infrared Spectroscopy (FTIR) as perthe ASTM D6645-01 method. A Thermo-Nicolet 750 Magna-IRSpectrophotometer equipped with OMNIC version 7.2a software was used forthe measurements.

Example 1

To a toluene solution (10 mL) of[(2-(OMe)C₆H₄)(2,4,6-Me₃C₆H₂)N]Hf(CH₂Ph)₃ (0.58 g, 0.83 mmol) was addeda toluene solution (10 mL) of t-Bu₃PNH (0.18 g, 0.83 mmol) dropwise over5 min at ambient temperature. The solution was stirred for 2 hours andthen concentrated to dryness under vacuum. The solid residue wastriturated with pentane and then concentrated again to dryness undervacuum. The crude product was isolated as an off-white solid with highpurity (0.65 g, 95%). ¹H NMR (toluene-d₈): 1.09 (d, J=12.7 Hz, 27H),2.12 (s, 6H), 2.21 (s, 3H), 2.26 (d, J=12.1 Hz, 2H), 2.34 (d, J=12.1 Hz,2H), 3.01 (s, 3H), 5.92 (dd, J=7.9, 1.4 Hz, 1H), 6.41 (dd, J=8.1, 1.1Hz, 1H), 6.50 (m, 1H), 6.71 (m, 1H), 6.73 (m, 2H), 6.82 (s, 2H), 6.92(d, J=7.4 Hz, 4H), 7.01 (m, 4H). ³¹P{¹H} NMR: 38.0.

Comparative Example 2

To a toluene solution (10 mL) of (t-Bu₃PN)TiMe₃ (0.16 g, 0.52 mmol) wasadded a toluene solution (10 mL) of [(2-(OMe)C₆H₄)(2,4,6-Me₃C₆H₂)NH(0.13 g, 0.52 mmol). The solution was stirred for 18 hours at ambienttemperature and then concentrated to dryness under vacuum. The residuewas slurried in pentane, cooled to −35° C., decanted and dried to givethe product in high purity as an off-white solid (0.23 g, 93%). ¹H NMR(toluene-d₈): 0.71 (s, 6H), 1.18 (d, J=13.2 Hz, 27H), 2.10 (s, 6H), 2.23(s, 3H), 4.00 (s, 3H), 5.94 (dd, J=8.0, 1.2 Hz, 1H), 6.64 (m, 1H), 6.79(m, 2H), 6.82 (m, 2H). ³¹P{¹H} NMR: 29.5.

Comparative Example 3

To a toluene solution (10 mL) of Hf(CH₂Ph)₄ (1.92 g, 3.54 mmol) wasadded a toluene solution (40 mL) of t-Bu₃PNH (1.54 g, 7.09 mmol)dropwise at 0° C. over 10 minutes. The resulting yellow solution wasstirred at ambient temperature for 5 hours. The volatiles were removedunder vacuum and the brown oily residue was triturated and decantedseveral times with cold pentane (30 mL portions). The solid was driedunder vacuum and isolated as a pale yellow solid (2.66 g; 95%). ¹H NMR(toluene-d₈): 1.20 (d, J=12.3 Hz, 54H), 2.17 (s, 4H), 6.82 (tm, J=7.0Hz, 2H), 7.16 (m, 4H), 7.19 (m, 4H). ³¹P{¹H} NMR: 37.4.

Comparative Example 4

Comparative Example 4 was prepared using an analogous procedure toExample 3. The product was isolated as pale yellow solid (3.38 g; 94%).¹H NMR (toluene-cis): 1.22 (d, J=12.4 Hz, 54H), 2.23 (s, 4H), 6.85 (tm,J=7.2 Hz, 2H), 7.11 (m, 4H), 7.18 (m, 4H). ³¹P{¹H} NMR: 30.3.

Comparative Example 5

Comparative Example 5, [(2-(OMe)C₆H₄)(2,4,6-Me₃C₆H₂)N]Hf(CH₂Ph)₃, wasprepared as described by Murphy, V. et al. in J. Am. Chem. Soc. 2003,125, 4306-4317.

Semi-Batch Homopolymerization Experiments

Semi-batch homopolymerization experiments were conducted in a 1000 mLreactor equipped with a pitched blade impeller coupled with a gasentrainment impeller to maximize gas dispersion in the liquid. A baffleis installed in the reactor to enhance the turbulence within the liquid.Heating of the reactor is performed using an electric element heater.The entire system is housed in a nitrogen-purged cabinet to maintain anoxygen deficient environment during the polymerization process. Thereactor uses a programmable logical control (PLC) system with Specviewsoftware as a method of process control.

For Polymerization Runs 1 to 3, the reactor was heated to the targettemperature of 140° C. and charged with cyclohexane (400 mL). Thereactor was then pressurized to 110 psig with ethylene and allowed toequilibrate for 5 minutes. Solutions of catalyst materials were preparedin a glovebox and loaded via cannula into catalyst injection tubesequipped with solenoid-operated valves and fixed to the reactor head. Toinitiate the reaction, solutions of the procatalyst (dissolved in 5 mLof toluene; target concentration of 300 μM) and (Ph₃C)[B(C₆F₅)₄] (133 mgdissolved in 5 mL of toluene; target concentration of 360 OA) weresequentially injected into the reactor using an over-pressure of argonand the injections staggered by <5 seconds. The reaction pressure wasmaintained throughout the reaction by feeding ethylene on demand from a10 L ballast vessel that is continually monitored for temperature andpressure. Upon consumption of 500 mmol of ethylene or 300 seconds ofreaction time (whichever happened first), the reactor contents aredischarged through a bottom drain valve and heat-traced line (160° C.)into a cooled letdown vessel containing a deactivating solution. Thequenched reaction contents were allowed to dry in the fumehood followedby rigorous drying in a vacuum oven and the dried polymer was weighed.Data for semi-batch homopolymerization experiments (Polymerization Runs1 to 3) are shown in Table 1 and ethylene consumption profiles are shownin the FIGURE.

Continuous Solution Polymerization

Continuous polymerizations were conducted on a continuous polymerizationunit (CPU) using cyclohexane as the solvent. The CPU contained a 71.5 mLstirred reactor and was operated between 130 to 160° C. for thepolymerization experiments. An upstream mixing reactor having a 20 mLvolume was operated at 5° C. lower than the polymerization reactor. Themixing reactor was used to pre-heat the ethylene, octene and some of thesolvent streams. Catalyst feeds (xylene or cyclohexane solutions oftitanium phosphinimine complex, (Ph₃C)[B(C₆F₅)₄], and MMAO-7/BHEB) andadditional solvent were added directly to the polymerization reactor ina continuous process. A total continuous flow of 27 mL/min into thepolymerization reactor was maintained.

Copolymers were made at 1-octene/ethylene weight ratios ranging from0.15 to 0.5. The ethylene was fed at a 10 wt % ethylene concentration inthe polymerization reactor. The CPU system operated at a pressure of10.5 MPa. The solvent, monomer, and comonomer streams were all purifiedby the CPU systems before entering the reactor. The polymerizationactivity, kp (expressed in mM⁻¹·min⁻¹), is defined as:

$k_{p} = {\left( \frac{Q}{100 - Q} \right)\left( \frac{1}{\lbrack M\rbrack} \right)\left( \frac{1}{HUT} \right)}$

where Q is ethylene conversion (%) (measured using an online gaschromatograph (GC)), [M] is catalyst concentration in the reactor (mM),and HUT is hold-up time in the reactor (2.6 min).

Copolymer samples were collected at 90±1% ethylene conversion (Q), driedin a vacuum oven, ground, and then analyzed using FTIR (for short-chainbranch frequency) and GPC-RI (for molecular weight and distribution).Copolymerization conditions and copolymer properties for PolymerizationRuns 4 to 11 are listed in Table 2.

TABLE 1 Semi-batch Ethylene Homopolymerization Experiments AmountPolymer- Reactor Reaction Ethylene Activity g ization Pro catalyst [M] Btemp. pressure Reaction Consumed PE/(mmol Run. No. Example (μM) (fromborate)/M (° C.) (psig) time (min) (mmol) M · hr) 1 1 300 1.20 140 1100.67 540 13881 2 Comp. 3 300 1.20 140 110 5.00 443 1290 3 Comp. 5 3001.20 140 110 5.00 268 670 M = Group 4 metal

TABLE 2 Continuous Ethylene/1-Octene Copolymerization ExperimentsPolymer- Pro- Reactor k_(p) SCB/ ization catalyst [M] B temp. C2 flowC8/C2 C2 convn, (mM⁻¹. 1000C PDI, Run. No. Example (μM) (from borate)/M(° C.) (g/min) wt/wt Q (%) min⁻¹) by FTIR M_(w) M_(w)/M_(n) 4 1 8.151.20 140 2.10 0.50 90.38 443 12.5 61548 3.15 5 1 5.93 1.20 140 2.10 0.3090.69 632 7.6 92142 3.77 6 1 6.67 1.20 140 2.10 0.15 89.93 515 3.2108985 3.99 7 1 5.19 1.20 130 1.90 0.50 89.90 660 10.8 86604 3.75 8 134.81 1.20 160 2.70 0.50 90.78 109 14.9 28729 2.21 9 Comp. 2 3.70 1.20140 2.10 0.50 29.93 44 — — — 10 Comp. 3 37.04 1.20 140 2.10 0.50 53.4512 — — — 11 Comp. 4 8.89 1.20 140 2.10 0.30 26.21 15 — — — M = Group 4metal

What is claimed is:
 1. A complex having the formula (PI)(AE)ML₂, wherein: I) PI is a phosphinimine ligand defined by the formula:

wherein each R¹ is independently selected from a group consisting of a hydrogen atom; a C₁₋₃₀ hydrocarbyl radical, which hydrocarbyl radical is unsubstituted or further substituted by a halogen atom; a C₁₋₁₀ alkoxy radical; a C₆₋₁₀ aryl or aryloxy radical; an amido radical; a silyl radical or a germanyl radical; II) AE is an amido-ether ligand defined by the formula:

wherein: Q is a bridging group between oxygen, O, and nitrogen, N², and contains one or more atoms selected from group consisting of Group 13 to 16 elements; R² is a group containing 1 to 50 atoms selected from the group consisting of hydrogen and Group 13 to 17 elements; R³ is a group containing 1 to 50 atoms selected from the group consisting of hydrogen and Group 13 to 17 elements; and wherein the R² group optionally joins together with the bridging group Q; III) each L is an activatable ligand; and IV) M is a metal selected from the group consisting of Zr and Hf, and wherein N¹, N² and optionally 0 are bonded to M.
 2. The complex according to claim 1 wherein AE is an amido-ether ligand defined by the formula:

wherein: Q is a bridging group between oxygen, O, and nitrogen, N², and contains one or more atoms selected from group consisting of Group 13 to 16 elements; R² is a group containing 1 to 50 atoms selected from the group consisting of hydrogen and Group 13 to 17 elements; R³ is a group containing 1 to 50 atoms selected from the group consisting of hydrogen and Group 13 to 17 elements; and wherein the R² group optionally joins together with the bridging group Q; the oxygen atom O, and the nitrogen atom N², are substituents on adjacent atoms of an aryl group.
 3. The complex according to claim 1 wherein AE is an amido-ether ligand defined by the formula:

wherein: Q is a bridging group between oxygen, O, and nitrogen, N², and contains one or more atoms selected from group consisting of Group 13 to 16 elements; R² is a group containing 1 to 50 atoms selected from the group consisting of hydrogen and Group 13 to 17 elements; R³ is a group containing 1 to 50 atoms selected from the group consisting of hydrogen and Group 13 to 17 elements; and wherein the R² group optionally joins together with the bridging group Q; the oxygen atom O is contained in a furan ring.
 4. An olefin polymerization catalyst system comprising: A) an organometallic complex according to claim 1 and B) an activator.
 5. The olefin polymerization catalyst system according to claim 4 wherein the activator is selected from the group consisting of an aluminoxane; an ionic activator; and mixtures thereof.
 6. A process for the polymerization of olefins comprising contacting one or more C₂ to C₁₀ alpha olefins with the olefin polymerization catalyst system of claim 4 under polymerization conditions.
 7. The process of claim 6 wherein the one or more C₂ to C₁₀ alpha olefins consists of a) ethylene; and b) one or more olefins selected from the group consisting of 1-butene; 1-hexene; and 1-octene. 